avoid segfault when reading header of malformed commits

diff --git a/git-difftool--helper.sh b/git-difftool--helper.sh
index 0594bf7ca54c6b91d5f96dd86d8962e93459d004..e6558d101062929241cc30cd0272556c3164310b 100755 (executable)
--- a/git-difftool--helper.sh
+++ b/git-difftool--helper.sh
@@ -13,7 +13,8 @@ TOOL_MODE=diff
 should_prompt () {
        prompt_merge=$(git config --bool mergetool.prompt || echo true)
        prompt=$(git config --bool difftool.prompt || echo $prompt_merge)
-       if test "$prompt" = true; then
+       if test "$prompt" = true
+       then
                test -z "$GIT_DIFFTOOL_NO_PROMPT"
        else
                test -n "$GIT_DIFFTOOL_PROMPT"
@@ -37,18 +38,24 @@ launch_merge_tool () {
 
        # $LOCAL and $REMOTE are temporary files so prompt
        # the user with the real $MERGED name before launching $merge_tool.
-       if should_prompt; then
+       if should_prompt
+       then
                printf "\nViewing: '$MERGED'\n"
-               if use_ext_cmd; then
-                       printf "Hit return to launch '%s': " \
+               if use_ext_cmd
+               then
+                       printf "Launch '%s' [Y/n]: " \
                                "$GIT_DIFFTOOL_EXTCMD"
                else
-                       printf "Hit return to launch '%s': " "$merge_tool"
+                       printf "Launch '%s' [Y/n]: " "$merge_tool"
+               fi
+               if read ans && test "$ans" = n
+               then
+                       return
                fi
-               read ans
        fi
 
-       if use_ext_cmd; then
+       if use_ext_cmd
+       then
                export BASE
                eval $GIT_DIFFTOOL_EXTCMD '"$LOCAL"' '"$REMOTE"'
        else
@@ -56,8 +63,10 @@ launch_merge_tool () {
        fi
 }
 
-if ! use_ext_cmd; then
-       if test -n "$GIT_DIFF_TOOL"; then
+if ! use_ext_cmd
+then
+       if test -n "$GIT_DIFF_TOOL"
+       then
                merge_tool="$GIT_DIFF_TOOL"
        else
                merge_tool="$(get_merge_tool)" || exit